Distillation of tar and apparatus therefor



July 19, 1932. L. R. FoRREsT ET AL 1,868,470

` DISTILLATION 0F TAR AND APPARATUS THEREFOR File May 1o, 1927 s sheets-sheet 1 ATTQRNEYS July 19, 1932. L. R. FoRREs-r ET Al. 1,868,470

DISTILLATION OF TAR AND APPARATUS THEREFOR ATTORNEYS July 19, 1932- R. FoRRr-:sT ET AL 1,868,470

DISTILLATION OF TAR AND APPARATUS THEREFOR Filed May 10. 1927 5 Sheets-Sheet 3 ATTORNEYS Patented July 19, 1932 #UNITI-:D STATES PATENT o1-Fics LAURENCE RAYMOND FORBEST, 0F EAST ORANGE, NEW JERSEY, AND EARL BIDDLE CONKLIN, OF SYBAC'USE, NEW YORK, ASSIGNOBS T0 THE BARRETT COMPANY, Ol' NEW YORK, N. Y., A CORPORATION OF NEW JERSEY DISTILLATION 0F TAIR AND APPARATUS THEBEFOB Application tiled May 10,

This invention relates to improvements in the distillation of tars, and particularly to the utilization of the heat available in the gases produced in coal carbcnization plants to distill tar and to produce oils and pitches by such distillation. The invention Will be described especially with reference to itsapplication to coke ovens.

In the ordinary operation of by-product coke ovens, the gases produced by the coking operation pass from the individual ovens through uptake pipes and goose-necks to a collector main common lto the ovens of the battery. The gases, commonly 4known as ffoul gases, leave the ovens at high tem# perature, e. g., 600o C. to 7 00 C. or higher, and carry a considerable proportion of volatilized tars and oils. Ordinarily the gases are cooled as rapidly as possible bythe application of sprays of ammonia liquor or ammonia liquor and tar in the goose-necks and collector main, the temperature of the gases being thereby reduced. The rapid cooling causes separation of the tar containing the heavier oils in the collector main. Further cooling is effected in the cross-over main y which connects the collector main to the condensing system and an additional quantity of tar carrying both heavier and lighter oils is thus separated. The collected tar is shipped ordinarily from the coke-oven plant to a tardistillation plant for distillation and separation of the oils and the production of pitches ofl varying .qualities Handling losses, freight charges, and distillation costs including fuel and capital and maintenance eX- penses for the special equipment required for distillation add to the cost of production of the tar-distillation products.

It is an object of the present invention to provide a method and apparatus which permit the distillation of tar ata coke-oven 1827. Serial No. 190,320.

coke ovens is utilized to distill tar and to separate vaporizable oils therefrom by spraying or otherwise bringing lthe tar into ntimate contactwiththe hot coke-oven gases, for example, in a suitable still or stills disposed directly above the` oven or ovens. The tar to be distilled is preferably sprayed into the top of ,the still and is subjected therein in a finely divided condition to direct contact with the hot coke-oven gases. The transfer of heat from the gases to the finely divided tar results in the distillation and separation of the more readily vaporizable constituents, leaving a residue of pitch. The pitch thus produced is Withdrawn continuously from the still or stills to a collector main separate from the ordinary collector main and is recirculated therefrom to the still or stills while the main body thereof flows continuously through the collector main. pitch are thus repeatedly subjected to the heat of the hot coke-oven gases and the pitch produced is mingled with the flowing stream of pitch in the collector main so that the iinished pitch can be Withdrawn from one end thereof. By regulating the conditions of distillation, such as the kind and quality of the tar supplied and the amount thereof, the number of stills employed and the rate or circulation of the tar and pitch therefrom, the distil. lation can be regulated to produce pitch having the desired characteristics.

The tar to be distilled ma be tar produced by the coke-oven battery an recovered therefrom in the manner hereinbefore described or it may be tar from any other source. The raw tar can be fed at a constant rate at one end of the separate collector main and can bel withdrawn therefrom and circulated through the desired number of uptake stills, the pitch produced in the stills being returned continuously to the collector main and mingled w1th the tar and pitch flowing therethrough. Preferably the separate collector main should be provided with a number of bales formin separate compartmentsin the bottom thereo from which compartments the tar and pitch are withdrawn for circulation through the stills. The pitch in the stills is returned preferably `to the compartments from which 1t The tar and' was withdrawn. The body of tar and pitch in the collector main flows o ver the successive f bailles into the compartments from which it-is Withdrawn for circulation through the stills and the final product isremoved conis a itch having definite characteristics determined b the amount of distillation in the several stil s, the distillation bein regulatedto produce a itch of the quality esiredl.

The rate ofeed of thel raw tar ma be the rate of production of tar in the co e-oven plant in which case twenty-four hour continuous operation is assumed; or the rate of feed may be such as to permit the entire Working up of the coke-oven plant roduction of tar in an eight or ten hour perlod. The number of uptake stills to be operated depends upon the quality of pitch to be produced and the time intervalduring which the work is to be performed. If, for instance, it is desired to make a pitch of high meltin point and to limit the operation to an eig t or ten hour shift, more stills will be required than if the distillation is conducted throughout the entire twenty-four hour period. Any number of uptake stills may be provided and those not 1n use may be connected to the ordinary collector main, suitable valves bein provided to rmit the direction of the gas mto either the ordinary or the separate collector main as desired..

' As the result of the distillation in the uptake stills the coke-oven gases will be enriched in the volatile oil constituents of the tar and the gases carrying such volatile constitutents may be delivered to the separate collector main through goose-necks provided for that purpose. The temperature ofthe vases will be reduced somewhat by the transler of heat tothe tar in the uptake stills but they will enter the separate collector main still at relatively high temperature and further distillation of the tar and' pitch may occur in the collector mainby transfer of heat from the gases to the tar and pitch therein. Owin however, to the large colume of tar and pitch which fiows through the collector main the distillation therein will not result in the production of hard pitch such as would not flow through the main. The heavier pitch constituents produced by the distillation will be dissolved in and carried along bythe stream-of tar so that the collector main will remain free from solid hard products which might otherwise obstruct the flow of A tarand pitch therethrough.,

from still .at a temperature suiiciently high to Amaintain the volatile oils in the vapor -phase and such gases may be subjected then to cooling in suitable condensers to separate stills. Valves ma the oil constituents. The condensers employed may be ordinary condensers in. which all of the oil constituents are separated together or fractional condensers may `be used to permit the recover-yaoi separate oil fractions having the desired characteristics and ada ted for commercial uses'.

T 1e invention as described may be applied to an ordinary coke-oven plant without material modification of the structure and operation of such a plant. The plant may comprise a series of ovens connected by the usual uptakes and goose-necks to a collector main in which' the hot coke-oven gases are normally cooled by sprays of ammonia liquor or ammonia liquor and tar to rapidly reduce the temperature of the ases and to separate tar constituents there rom. The partially cooled gases may be delivered throughv a cross-over main of the usual type to the or- `-dinar condensing system. The ases may be coole by sprays of ammonia llquor in. the cross-over main and in the condensers to separate further quantities of tar'v and oils therefrom. The tar and oils thus recovered ma be separated from the ammonia liquor vWliic may in part be treated for the recovery of ammonia and in part returned `for further' cooling use in the collector main. The separated tar may be delivered'then to the distillation systemV as herein described for distillation and separation of the oil constituents. The gases freed from tar and the heavier oil constituents can be treated in the usual recovery system to separate light oils and other valuable constituents and can be utilized then as fuel gas as is customary in cokeoven plants.

The up-take stills and separate collector main whlch are employed to eiiect the distillation of the tar in accordance with the present invention may be disposed preferab y at the rear of the ovens so that they do not interfere with the ordinary operation of the cokeoven plant when the stills are not in operation. All of the coke ovens may be connected to the usual collector main and separate uptake pipes may be provided for the then be used to divert the coke-oven .gases lnto the ordinary collector 'main or into the stills as desired. When no tar is being distilled `the ases from all of the ovens will be sub'ecte in the ordinary collector main to cooling as herebefore described and thereafter to further cooling in the cross-over main and condensers to rel cover tar and oil constituents of the gases. When tar is being distilled the gases from the ovcnspwhich are connected to the stills will pass therethrough, being utilized therein for the distillation of tar. The gases and vapors resulting from such distillation will be cooled se arately to separate the oil constituents. fter such separation the remaining gases can be delivered to the usual Acondensing; system and mingled with the gases from the remaining ovens.

The operation as described is applicable generally to plants of variouskinds designed for the distillation of coal, but it will be described more particularly with reference to a coke oven of the Semet-Solvay type. In the accompanying drawings,

F ig. 1 is a plan view of ay coke oven including the usual condensing equipment and having uptake stills as hereinbefore described for the distillation of tar; v

F ig. 2 is an elevation, partly in section, of the structure illustrated in Fig. 1,-

F ig. 3 is an enlarged sectional vievv of an uptake still with the separate collector main connected thereto;

Fig. Ll is afplan vievvv of a series of uptake stills with the separate collector main; and

F ig. 5 is a side elevation as illustrated in Fig. e

Referrin 1 to the drawings, 5 indicates the coke oven attery having a plurality of individual ovens 6, each of which is provided with an uptake pipe 't' and goose-neck 8, the latter being connected to the usual collector main 9 so that the gases from the ovens are delivered directly to the collector main. 'lhe collector main and the goose-necks leading thereto may be provided with spray nozzles 1G to permit the introduction or" ammonia liquor or ammonia liquor and tar for the purpose orr1 cooling the gases as hereinbetore described. 'lhe ammonia liquor and tar and the uncondensed gases pass through a crossover main 1l in which further cooling may he effected. The tar and ammonia liquor are withdrawn from the cross-over main and are separated in a decanter 12. The ammonia liquor is normally returned in part to the collector main in the form of a continuous circulation, a part being diverted to the ammonia distillation system of the recovery o1 ammonia. The tar can be collected in a tank 13 :tor use as hereinafter described. The gases :trom the cross-over main are delivered to condensers lll wherein they are cooled, for example, by direct Contact with ammonia liquor for the purpose of separating the oil constituents therefrom. The oil and ammonia liquor are separated in a decanter lil. rlhe ammonia liquor may be utilized as desired in the system and the oil which is usually more or less contaminated with tar con.- sti-tuents may be mixed with the tar in the tank 13 for distillation in accordance with the invention, or may be separately distilled in the same or similar equipment in an opera- A tion distinct from that handling the heavier tars normally recovered from decanter 12. rlhe gases from the condensers 14 are Withdrawn through an exhaustcr 15 which maintains the pressure balance in the system and may be delivered thence tothe usual equipment for the recovery of ammonia and other or the structurel the collector main.

valuable constituents of the gases which are delivered then to a gasometer for use as fuel or for other purposes.

For the urpose of the present invention a number ot the coke ovens are provided with uptake pipes 16 connected thereto at the rear of the ovens. These uptake pipes communicate with casings 17 forming the uptake stills and provided with baffles 18 which prevent descent of tar into the uptake pipes. The tar to be distilled is introduced to the casings through nozzles 19 and pipes 2() leading thereto. Each ofthe casings is provided with clean-'out doors 20 and 21 whereby access to the interiors is obtained for the purpose of removing any accumulation of hard material. rlhe uptake stills illustrated are those covered by the application of George E. Brandon, Serial No. 154,746, tiled December 14,1926.

The stills communicate through goosenecks 22 with a separate collector main 23 which is thus adapted to receive all of the gases and vapors from the uptake still. -llach or" the stills communicates likewise through a pipe 24 with the collector main to permit the direct return of the partially distilled tar or pitch :trom the uptake still to the collector main. Accumulation ot pitch in the still is thus avoided.

The collector main is provided with a plurality of bafes 28 extending across the bottom thereof and to a suitable height Awhich dcterrninesthe level of the tar and pitch in Additional baes 24' are disposed in the Collector main but do not extend to the bottom thereof. The tar or pitch flowing through the collector main is caused to ollovv a path over the battles 23 and under the batidos 2e', the ballles 23 dividing the collector .main into a series of conipartments in which the tar and pitch are temporarily held.

@pposite each compartment a pump 25 is connected by an inlet pipe E26- to the collector main. The pump delivers the tar or pitch through a pipe 27 to the spray nozzle in the corresponding uptake still and thus maintains a circulation of the tar or pitch between the uptake still and the collector main. A screen 28 is disposed in a suitable casing 29 in the pipe leading to the spray nozzle for purpose of separating any solid matter which might otherwise prevent the proper operation or" the system. The screen may be cleaned from time to time as required by steam supplied through a pipe provided for that purpose, a suitable drain connection being also provided to carry away material thus removed from the screen.

The tar to be distilled is Withdrawn from the tank 13 hereinbefore described or from any suitable source and is pumped or otherwise conveyed to the inlet to the separate collector main to which it is introduced through a sealed connection 29. The tar Hows thus into the first compartment of the collector main and is circulated by the pump through the first uptake still wherein lt'vis subjected to the distilling effect of the ht poke-oven gases and is thus relieved of a portion of the volatile constituents. The partially distilled tar returns immediately through the connection 24 to the first compartment of the c0l, 4lector main and mingleswith` the fresh tar flowing into the collector main. A portion of this mixture of tar and pitch overflows continuously into the second compartment and is circulated therefrom through the second uptake still with resulting further distillation and removal of a portion of the volatile constituents. The partially distilled pitch from the second uptake still returns to the second compartment of the collector main the rate of flow of tar through the collector main and the rate of recirculation through the stills. The product, consisting of pitch of the desired consistency, is withdrawn through a pipe 30 and pitch useal 31' from which it may be delivered to any suitable storage receptacle. The rate of circulation of the tar vthrough the uptake stills mayexceed materially the rate of l'ow of tar through the collector main so that .the tar and pitch are subjected repeatedly to the distilling efect of the coke-oven gases during its passage through each successive compartment and the uptake stills connected therewith.

The separate collector main is provided with a gas-outlet pipe 32 at one end thereof through which thecoke-oven Vgases partially cooled by Contact with the tar and pitch in the uptakev stills and collector main and carrying the vapors produced by .the distillation of tar arecwithdrawn. This pipe may be connected to a separate condensing system including, for example, the fractional condensers 38 in which the oil constituents o the gases are separated and withdrawn therefrom. Such oil constituents may be recov ered substantially free from contamination with tarry matter so that the oils are utilizable as recovered for Various commercial purposes. The gases, after cooling and separation of the oils, may be delivered through a pipe 34 to the main gas stream as it enters the exhausters, the combined gases being then treated for the recovery of ammonia and other valuable constituents-before delivery to the gasometer for storage. v

Among the advantages of the method and apparatus as described are the possibility of closely regulated control of the amount of distillation and the character and quality -of the pitch produced, the low initial cost of the apparatus required owing to the elimination of excessive piping systems, and particularly the avoidance of plugging of the pipes through which the tar and pitch are conveyed. The operation is a continuous and not a batch process. This is of itself a marked advantage from an operating standpoint and Jfrom the product standpoint, duel to the fact that for any one type of pitch production, the oils condensed in the separate condensing system, if such is used, are of uniform quality throughout the operation. lln the production of pitches by the `batch process, the oils carried by the cokeoven gases following their contact with the tar or pitch spray, undergo a continuous quality change, as the devolatilization of the tar progresses. Operation by the method described herein is productive of a'much more constant oil quality, this characteristic being augmented in proportion to the number of stills required for the operation. rillhese and other advantages permit the economical 0peration of the system to produce pitch and valuable 1toy-.product oils directed at the cokeoven plant and `the utilization or the heat which is normally wasted for the production of these products.

Various changes may be made in the details of the operation as described and in the apparatus employed without departingA from the invention or sacrificing any of the advantages thereof.

We claim 1. the method of distilling tar at a coke oven plant in the ovens of which coal is distilled which comprisespassing the fresh hot distillation gases from the ovens through stills to a collector main, maintaining a' stream of tar and pitch in the collector main by adding tar to one' end of the mainy and withdrawing pitch from the other end of the main, withdrawing a part only of the stream from the main at each of a plurality of spaced intervals along the main at whichthe composition o the stream in the main is dierent and separately subjecting the material withdrawn ateach interval to distillation by contact with the hot gases in one of the stills, returning the distillation residue from the stills to the main, thereby gradually converting the tar to pitch.

2. The method of distilling tar to pitch which comprises maintaining i a iowing stream of tar and pitch, adding fresh tar to the stream andgradually converting it to pitch by successively withdrawing and subjectmg different portions of the stream to distillation in stills utilizing dierent portions of fresh coke oven gases as the heating medium, and.' returning the distillation residue from the several stills to the stream so as to progressively increase the pitch content of the stream.

3. Apparatus for distilling tar, comprising a collector main, a plurality of batlles dividing the main into zones, a like number of stills, gas means connecting each still with a different zone of the main, means for passing gases from the coal distilling means to the stills, means for withdrawing tar and pitch 'from the several zones of the main between the respective ballles and for delivering it to the stills and means for returning pitch produced in the stills to the several zones of the'main.

4. The Abyproduct recovery system of a coal distillation plant, which comprises a gas collector main, a number of stills connected by gas mains with the collector main, means for passing gases from the ovens to the stills, means for supplying tar to one end of the main and withdrawing pitch from the other end of the main, and means for \vith,

drawing portions of the material through the lnain at `successive intervals along the main and bringing them into the stills to subject thrni to distillation therein.

5. The by-product recovery system of a coal distillation plant, which comprises a gas collector main, aI number of stills connected by gas mains with the collector main, means for passing gases from the ovens to the stills` means for supplying tar to one end of the main, means for withdrawing portions ot the material from the main at successive intervals along the main and bringing them into the stills, and means for returning the residue from the stills to the main.

In testimony whereof I affix my signature.

LAURENCE RAYMOND FORREST.

ln testimony whereof I affix my signature.`

EARL BIDDLE CONKLIN. 

